when a method is declared in the class along with a
using declaration and the using declaration is declared before
the method that implemented the pure virtual method, such as:
struct ConcreteDerived : AbstractBase {
ConcreteDerived() {} // was not wrapped
using AbstractBase::f;
virtual void f(int n) override {}
};
SourceForge bug: https://sourceforge.net/p/swig/bugs/932/
check_implemented in allocate.cxx was correctly finding a
non-abstract method, however, Swig_symbol_clookup_local_check, was
using the using declaration node instead of using the node returned
by check_implemented. The checkfunc is now given more control by
returning the node to use rather than Swig_symbol_clookup_local_check
always using the head of the csym linked list.